Constant frequency escapement mechanism



Nov. 22, 1966 ca. 5. WESTERMAN 3,286,633

CONSTANT FREQUENCY ESCAPEMENT MECHANISM Filed Sept. 5, 1964 2Sheets-Sheet 1 Fig/ INVENTOR.

GEORGE S. W STERMAN 7 i ATTORNEYS Nov. 22, 1966 ca. S..WESTERMAN3,286,633

CONSTANT FREQUENCY ESCAPEMENT MECHANISM Filed Sept. 5, 1964 2Sheets-Sheet 2 -62 69' ml HHHIH I! J? 7 W t? INVENTOR. 34 7 7 GEORGES.WESTERMAN 3 37' BY m M44. WM

7 ATTORNEYS United States Patent 3,286,633 CONSTANT FREQUENCY ESCAPEMENTMECHANISM George S. Westerman, Cinnaminson, N..I., assignor to theUnited States of America as represented by the Secretary of the ArmyFiled Sept. 3, 1964. Ser. No. 394,367 4 Claims. (Cl. 102-84) Theinvention described herein may :be manufactured and used by or for theGovernment for governmental purposes without the payment to me of anyroyalty there- This invention relates to timing mechanisms and, moreparticularly, to timing mechanisms associated with projectile fuzes.

In time movements of mechanical time fuzes, the escapement area thatmeters out time is a most critical one. Normally, a block, which isadjustable to a predetermined set position, supports the free ends of ahairspring that controls the beat frequency or oscillation of theescapement lever in the timer. However, when subjected to high speedrotational environment, the hairspring has a tendency to stiffen fromthe effects of centrifugal force resulting in a decrease in itsdeflection, which in turn increases the beat frequency, The increase inbeat frequency normally makes the timing movement run faster than thatfor which it had been adjusted. Thus, when precision timing is requiredparticularly in a projectile fuze environment, a deviated setting of thetimer from its regulated adjustment is necessary in the field. Thepresent invention eliminates the need for such deviated settingsheretofore required in the field for use in a high spin environment.

A primary object of the invention is to provide a timing mechanismadapted to operate at a constant predetermined tbeat frequency whensubjected to variable speed effects of rotation.

A further object of the invention is to provide an arcuate timingmechanism capable of compensating for tendencies of its hairspringfrequency to deviate when placed in a dynamic environment.

These and other objects and advantages of the invention will becomeapparent from the following description and accompanying drawings inwhich:

FIG. 1 is an elevational view partly broken away in section to show thetiming mechanism of a projectile fuze;

FIGJZ is a sectional view taken along line 22 of FIG. 1;

-FIG. 3 is an enlarged perspective view of a preferred supportarrangement for an end of the hairspring shown in FIG. 2;

FIG. 4 is an elevational view of the firing pin locking arrangement;

FIG. 5 is a sectional elevation view of the adjustable arrangementsupporting a hairspring end; and

FIG. 6 is a view similar to FIG. 2 with certain parts removed and othersenlarged showing the escapement area of the mechanism,

The projectile fuze, generally shown at 10 (FIG. 1), is provided withrearwardly located attaching or threaded means 11 for connection to aforward portion of projectile body 12 as the forward nose portionthereof. The timer mechanism or movement assembly shown generally at 13is mounted within the fuze for rotation therewith as the projectilespins during its flight. The mechanism 13 includes a spirally woundspring 14 having its outer end attached or secured to a fixed internalmember 16 and its inner end connected to central shaft 18 rotatablypositioned about a longitudinal axis of the fuze. Gear 20 carried byshaft 18 is interconnected by gear train elements 21, 22, 23, 24, 25, 26to escapement gear 27 which is driven by gear 26 carried by common shaft28. Escapement gear 27 (FIGS. 2, 6) is thus biased by the stored'energyin spirally wound spring 14 for rotation as controlled by the pallets30', 31 of an oscillating escapement lever 32. The radially centralportion 35 of shaft 33 carrying escapement lever 32 is rigidly connectedto hairspring 34 substantially at the mid-point thereof. Each of thehairspring free ends 36, 37 is positioned in appropriate slots orgrooves 38 (FIGS. 3, 6) of an upstanding leg member 39 of an adjustableand self-compensating support arrangement generally shown at 40 (FIGS.3, 5, 6) and to be more fully described hereinafter.

Referring again to FIG. 1, firing pin 41 is cocked with its shaft 42spring loaded and which when released will ignite detonator 43.Compression spring 44 on shaft 42 is compressed between shaft collar 45and a suitably recessed shoulder 46 on a stationary member of themovement assembly 13. A locking cam 47 (FIGS. 1, 4), for normallyretaining collar 45 in a retracted position, is pivotally carried bypost 48 suitably journalled in fixed or stationary members or plates 49of the movement assembly. A torsion spring loaded shaft 50 (FIG. 4),appropriately journalled in stationary movement assembly members,normally engages cam 47 in the cocked position of firing pin collar 45until the timing mechanism has run its predetermined time when acircumferential opening 52 in timing disk 53 rotated by shaft 18 isaligned with and receives an offset projection 54 of the thusly rotatedshaft 50. Minute predetermined rotation of shaft 50 and recess 55therein will immediately free cam 47 to be withdrawn from locking thefiring pin collar 45, enabling the spring biased firing pin 41 to stabor ignite the detonator.

Preferably, each hairspring end 36, 37 is provided with a supportarrangement 40 having an upstanding slotted leg 39 that is confined tomovement along a predetermined straight line extending through thehairspring and escapement lever central connection 35, and whichslidingly supports its respective hairspring end at respective positionssuch that the central connection 35 is at all times equidistanttherefrom. Each of the support arrangements 40, symmetrically positionedabout the hairspring and lever connection 35, includes a housing orblock body (FIGS. 3, 5, 6) which preferably has formed in its uppersurface a centrally located, longitudinally extending slot 61 thatcommunicatively intersects with a lengthwise, central cylindrical boreor passageway 62. The passageway 62 is closed at one end 63, butotherwise extends substantially the full length of the housing. The openend of the passageway has intersecting lateral openings for containing apin 64' to retain a transversely apertured cover plate 64 in securedposition, after a controlled defiection spring 65 and a cylindricalblock 66 have been inserted in their appropriate positions. The closedend 63 preferably is counterbored to satisfactorily retain spring 65 ina desired central position biasing cylinder 66 against cover plate 64,and cylinder 66 is formed with a threaded lateral surface opening toreceive appropriate mating threads 67 on the bottom of support leg 39which passes through slot 61. A longitudinal threaded bore 68 isprovided in the lower central portion of each housing and receives acorresponding threaded adjusting screw 69 which is retained in properposition by its collar 69 in an appropriate keeper '70. A slot 71 in thehead end of each screw 69 enables each of the housings 60 to beindependently adjusted lengthwise of the hairspring 34 and relative tothe connection 35.

With the foregoing construction it should be apparent that after eachsupport leg 39 has been basically adjusted to a predetermined regulatedposition relative to the hairspring, further adjustments in the fieldare no longer necessary to compensate for subsequently predicted highspin environments since centrifugal force developed will urge thecylinders 66 outward against the respective deflection springs 65. Theresulting outward movement of legs 39 increases the effective length ofthe hairspring to compensate for any tendency that centrifugal forceeffects would have upon the beat frequency of the timer. Thus, thehairspring can maintain its normal reciprocatory movements betweendeflected S positions, one of which is shown in dotted linesillustrating the hairspring ends 36, 37 (FIG. 6), in assisting theescapement lever to accurately control the metering of timer poweroutput.

Various modifications or changes may 'be resorted to without departingfrom the scope of the invention as defined in the appended claims.

I claim:

1. A timing mechanism for a projectile fuze comprising, an oscillatoryescapement lever for metering timer power output, a hairspring connectedto said lever and controlling the oscillation thereof, means slida'blymounted for reciprocatory movement substantially along a line extendingthrough said hairspring and lever connection and supporting end portionsof said hairspring, and mean biasing said supporting means toward saidconnection, so constructed and arranged that when the timing mechanismis subjected to high speed rotation, said supporting means will maintaina substantially constant predetermined beat frequency therein.

2. A timing mechanism as defined in claim 1 in which said supportingmeans are provided with independently adjusting means.

3. In a projectile fuse timing mechanism having an oscillatoryescapement lever for metering timer power output, a hairspring having acentral portion connected to a central portion of said lever andcontrolling the oscillation of said lever, and means supporting endportions of said hairspring, said support means including a pair ofhousings each having a passageway substantially symmetrically positionedabout a common center line passing through said lever and hairspringconnection, a movable block in each passageway, means in each passagewaybiasing one end of the :block therein towards said connection, and meansconnected to each block and slidingly receiving a respective hairspringend portion, by virtue of all of which each block may be moved againstits biasing means for adjusting the effective lengths of said hairspringto maintain a substantially constant predetcnmined beat frequency in thetiming mechanism when the latter is subjected to high speed rotation,

4. The structure recited in claim 3 wherein said housings are adjustablealong said common center line.

References Cited by the Examiner UNITED STATES PATENTS 2,226,669 12/1940 Perrenoud 10284 2,406,730 8/1946 Whitehead 581 17 3,168,833 2/1965Popovitch 102-84 X BENJAMIN A. BORCHELT, Primary Examiner. G. H.GLANZMAN, Assistant Examiner.

1. A TIMING MECHANISM FOR A PROJECTILE FUZE COMPRISING, AN OSCILLATORYESCAPEMENT LEVER FOR METERING TIMER POWER OUTPUT, A HAIRSPRING CONNECTEDTO SAID LEVER AND CONTROLLING THE OSCILLATION THEREOF, MEANS SLIDABLYMOUNTED FOR RECIPROCATORY MOVEMENT SUBSTANTIALLY ALONG A LINE EXTENDINGTHROUGH SAID HAIRSPRING AND LEVR CONNECTION AND SUPPORTING END PORTIONSOF SAID HAIRSPRING, AND MEANS BIASING SAID SUPPORTING MEANS TOWARD SAIDCONNECTION, SO CONSTRUCTED AND ARRANGED THAT WHEN THE TIMING MECHANISMIS SUBJECTED TO HIGH SPEED ROTATION, SAID SUPPORTING MEANS WILL MAINTAINA SUBSTANTIALLY CONSTANT PREDETERMINED BEAT FREQUENCY THEREIN.